We want to know how to identify "valid nutrition info in the news" so we'll have some idea who to believe since this is one of the main ways people get their nutrition information.

The following article also has some good tips on making sense of nutrition studies, "How to make sense of the constant onslaught of nutrition studies", Leslie Beck, January 2015

A.   Know the type of research being reported and what conclusions can be made:

(The following information was modified from Brain Lindshield's Kansas State University Human Nutrition (FNDH 400) flexbook. goo.gl/vOAnR)


1. Observational Study- simply monitoring and/or collecting information. No treatment is given. The researcher is simply COLLECTING INFORMATION. These types of studies are used to assess disease trends or nutritional habits of large populations and determine the factors that may influence these phenomena. Keep in mind these studies do not prove cause and effect, they only indicate relationships between factors. For example your text mentions that smoking and low vegetable intake appear to be related in some studies, but this does not mean that smoking cigarettes causes people to eat fewer vegetables or that eating fewer vegetables causes people to smoke.

2. Epidemiological Study- Epidemiology is defined as the study of human populations. These studies often investigate the relationship between dietary consumption and disease development.  These people were/are NOT given a treatment.  There are three main types of epidemiological studies: cross-sectional, case-control, and prospective cohort studies. Below case control studies are discussed in more detail.
 

Case control studies look at a group of cases (e.g. people with a disease) vs. controls (people without the disease). Most case-control studies are retrospective (looking back in time, or looking at the past). These studies try to determine if there were differences in the diets of the cases compared to controls in the past. Cases and controls are matched on characteristics such as age, sex, BMI, history or disease among others. This means researchers try to choose a control that has similar characteristics to the case. The researchers then compare the exposure levels between the cases and controls as shown below. In this example a greater proportion of diseased (cases) individuals than disease-free individuals (controls) are exposed to something.

Above is an example of a case-control study in which the diseased were more likely to have been exposed than those who were disease-free. Cases are represented by the red box on the left, and the controls are the green box on the right.

Using trans-fat intake as the exposure, and cardiovascular disease as the disease, the figure would be expected to look like this:

To determine peoples' intakes of foods and food components, food frequency questionnaires are commonly used. As the name suggests, a food frequency questionnaire is a series of questions that determines how frequently you consume a certain food. An example of a question on a food frequency questionnaire is shown below:

"Over the past 12 months, how often did you drink milk?"

Never

1 time/month         less 1 time/day

2-3 times/month    2-3 times/day

1-2 times/week     4-5 times/day

3-4 times/week     6 or more times/day

5-6 times/week

An example of a food frequency questionnaire is shown in the link below.

Case-control studies are a type of observational study. So as mentioned above, these studies do not prove cause and effect, they only indicate relationships between factors. 

These type of studies do have drawbacks because they are relying on someone's memory. Can you remember over the past 12 months how often you drank milk?

Animals can be used in research that would be unethical to conduct in humans. Researchers can make sure that a certain regimen is safe before it is researched in humans. One advantage of animal dietary studies is that researchers can control exactly what the animals eat. In human studies, researchers can tell subjects what to eat and provide them with the food, but that does not necessarily mean that they are going to consume exactly what they are supposed to. Also people are not great at estimating, recording, or reporting how much or what they eat/ate. Animal studies are also normally far less expensive than human studies. There are some important factors to keep in mind when interpreting animal research. First, an animal’s metabolism and physiology is different than humans. As a result, animals' absorption and bioavailability of compounds can differ from humans. Furthermore, animal models of disease (cancer, cardiovascular disease etc.), although similar, are different from the human disease. So these factors have to be considered when interpreting results from this type of research.  Animal research should not make unfounded links to people. Nevertheless, animal studies have been, and continue to be, important for nutrition research.

Definition of a treatment: something given (like a supplement/certain food/advice) OR something done (like massage or physical therapy).

There are a variety of human intervention study designs in nutrition research, but the most common, especially in pharmaceutical/medical research, is the clinical trial. A clinical trial is a scientifically controlled study using consenting people to find the safety and effectiveness of different items/regimens. Clinical trials are the "gold standard" research method. Their findings carry the most weight when making decisions about a certain research area because they are the most rigorous scientific studies. Every pharmaceutical must go through a series of clinical trials before being approved for the market by the FDA (specifically the randomized, double blind, placebo controlled experiments). Human intervention studies/clinical trials are normally prospective.

Placebo and The Placebo Effect- A placebo is a fake pill or treatment that serves as a comparison to an active treatment. The use of a placebo is necessary in medical research because of a phenomenon known as the "placebo effect". The placebo effect results from a subject's belief in a treatment, even though there is actually no treatment being administered. So a healing response can happen as a result of treatment, not the treatment itself.  An example would be an athlete who consumes a sports drink and runs the 100 meter dash in 11.00 seconds. The athlete then, under the exact same conditions, drinks what he is told is "Super Duper Sports Drink" and runs the 100 meter dash in 10.50 seconds. But what the athlete didn't know was that Super Duper Sports Drink was the Sports Drink + Food Coloring. There was nothing different between the drinks, but the athlete believed that the "Super Duper Sports Drink" was going to help him run faster so he did. This improvement is the placebo effect.

Randomization- Randomization is the process of randomly assigning subjects to groups to decrease bias. Bias, according to Merriam Webster, is "a systematic error introduced into sampling or testing by selecting or encouraging one outcome or answer over others". Bias can occur in assigning subjects to groups in a way that will influence the results. An example of bias in a study of an antidepressant drug is shown below. In this nonrandomized antidepressant drug example, researchers (who know what the subjects are receiving) put depressed subjects into the placebo group, while "less depressed" subjects are put into the antidepressant drug group. As a result, even if the drug isn't effective, the group assignment may make the drug appear effective, thus biasing the results as shown below.

This is a bit of an extreme example, but even if the researchers are trying to prevent bias,
sometimes bias can still occur. However, if the subjects are randomized, the sick and the
healthy people will ideally be equally distributed between the groups. Thus, the trial will be unbiased and a true test of whether or not the drug is effective.



Blinding- Blinding is a technique to prevent bias in human intervention studies. A study without blinding is referred to as "open label" because both the subject and the researchers know what treatment the subject is receiving (i.e. placebo or drug). This can lead to bias, so these types of trials are used less frequently.

In a single blind study, the researcher knows what treatment the subject is receiving, but the subject does not. If the subjects are randomized, these types of trials should produce robust results, but it is still possible that the researcher can bias the results.

Finally there is the double blind study, where neither the researcher nor the subject know what treatment the subject is receiving. A separate board reviews the collected results and decides the fate of the trial. This is the "gold standard" because it prevents observer bias from occurring.

B. Ensure researcher (who might not be the author) has good credentials

C. Consider who funded the Study

D. Make sure research is Published

After nutrition researchers have obtained their results, they want to disseminate them, or let people know what they found. The primary way they do this is by publishing their results in journals. The researchers put together a paper explaining their experiment and findings in a journal article. An article’s primary components are normally an introduction, abstract, methods, results, and discussion/conclusion. They submit the paper to a chosen journal and the journal editor then selects expert researchers who will critically review the article. These reviewers make sure that research published in journals is of good quality and of interest to readers. In more rigorous journals the article might also need to meet a certain theme of an issue that a journal wants to publish. This is a rigorous process that is humorously depicted by the below cartoon.

To give you an idea of how rigorous this process is, let's consider some major nutrition journals.

Journal of Nutrition (JN)

American Journal of Clinical Nutrition (AJCN)

Journal of the Academy of Nutrition and Dietetics (formerly Journal of the American Dietetic Association)

Nutrition Reviews

Annual Reviews of Nutrition

British Journal of Nutrition

European Journal of Clinical Nutrition

There are two major nutrition societies in the US: The American Society for Nutrition (ASN) and the Academy of Nutrition and Dietetics (AND, formerly the American Dietetic Association). ASN publishes the Journal of Nutrition and the American Journal of Clinical Nutrition, while AND publishes the Journal of the Academy of Nutrition and Dietetics. If you want to see more about the major nutrition societies, use the following links.

The following table contains 2 measures, impact factor and acceptance rate for these journals. The impact factor is a measure of influence of the journal. This measure indicates how many people read the articles that are published in that journal. The acceptance rate is the % of articles that are submitted that are actually accepted for publication.

Table 1.61 Selected nutrition journal impact factors and acceptance rates

The acceptance rate for three of these journals ranged from 25-40%. Thus, the majority of submitted articles are rejected and sent back to the researchers. To put nutrition journals in perspective, some of the top medical and science journals with a broad following have impact factors as high as 75 and an acceptance rate of 5-10%.

Hopefully these numbers help you understand that peer review is a rigorous process where peer reviewers "tear the article to pieces."

They do not physically shred the article (it is all done online), but there are often extensive revisions to make (maybe even multiple times) before the paper can be published, if you're so lucky. Generally, the more difficult it is to get a paper accepted into a journal, the more solid the research must be. Most of the information on the internet has not gone through peer review and should be explored with some caution.

The below video clearly depicts the peer review process.

Here is a link to the above video:  https://youtu.be/rOCQZ7QnoN0